network management - cse.wustl.edujain/cse473-11/ftp/i_9mgm.pdf · washington university in st....

9-1©2011 Raj JainCSE473sWashington University in St. Louis

Network ManagementNetwork Management

Raj JainRaj JainWashington University in Saint Louis

Saint Louis, MO [email protected]

Audio/Video recordings of this lecture are available on-line at:http://www.cse.wustl.edu/~jain/cse473-11/


OverviewOverview

q What is Network Management and How?q ASN.1q Management Information Base (MIB)q SNMP: Protocol, Message formatsq SNMP V2Note: This class lecture is based on Chapter 9 of the textbook

(Kurose and Ross) and the figures provided by the authors.


What is Network Management?What is Network Management?q Traffic on Network = Data + Control + Managementq Data = Bytes/Messages sent by usersq Control = Bytes/messages added by the system to properly

transfer the data (e.g., routing messages)q Management = Optional messages to ensure that the network

functions properly and to handle the issues arising from malfunction of any component

q If all components function properly, control is still required but management is optional.

q Examples:q Detecting failures of an interface card at a host or a routerq Monitoring traffic to aid in resource deploymentq Intrusion Detection


Components of Network ManagementComponents of Network Management1. Performance Management:

Measure, report, analyze, and control traffic, messages2. Fault Management:

Detect, log, and respond to fault conditions3. Configuration Management:

Track and control which devices are on or off4. Accounting Management:

Monitor resource usage for records and billing 5. Security Management:

Enforce policy for access control, authentication, and authorization


How is Network Managed?How is Network Managed?

q Management = Initialization, Monitoring, Controlq Manager, Agents, and

Management Information Base (MIB)

NetworkMIB Agent

NetworkManagementStation

MIBAgent

MIBAgent


Example of Network ManagementExample of Network Management

Router(Agent)

Router(Agent)

Router(Agent)

Management Server(Manager)

Agent

Agent


Internet Management FrameworkInternet Management Framework

1. Structure of Management Information (SMI):Data definition language for objectsASN.1 was defined by ISO and is used in SNMP.

2. Management Information Base (MIB):Distributed network management data

3. SNMP protocol: Manager Managed object communication

4. Security, administration capabilities:Major addition in SNMPv3


ASN.1ASN.1

q Abstract Syntax Notation Oneq Joint ISO and ITU-T standard, Original 1984, latest

2002.q Used to specify protocol data structuresq X.400 electronic mail, X.500 and LDAP directory

services, H.323 VOIP, SNMP, etc use ASN.1q Pre-Defined: 1=Boolean, 2=Integer, 3=Bit String,

4=Octet String, 5=Null, 6=Object Identifier, 9=Realq Constructed: SEQUENCE (structure), SEQUENCE

OF (lists), CHOICE, ...


SMI Base Data TypesSMI Base Data TypesData Type Description INTEGER ASN.1 32-bit integer between -231 and 231-1 Integer32 32-bit integer between -231 and 231-1 Unsigned32 Unsigned 32-bit integer between 0 and 232-1 OCTET STRING ASN.1 byte string for binary or text up to 65,535 bytes

long OBJECT IDENTIFER

ASN.1 format administratively assigned object identifier

IPaddress 32-bit Internet address in network-byte order Counter32 32-bit counter that increases from 0 to 232-1 and wraps to

0 Counter64 64-bit counter Gauge32 32-bit integer that does not count above 232-1 or below 0 TimeTicks Time interval measured in 1/100th of a second Opaque Uninterpreted ASN.1 string (needed for backward

compantibility)


ASN.1 ExampleASN.1 ExampleAddressType ::= SEQUENCE {name OCTET STRING,number INTEGER,street OCTET STRING,city OCTET STRING,state OCTET STRING,zipCode INTEGER}


Encoding RulesEncoding Rules

q ASN.1 only specifies the structure.q Encoding rules indicate how to encode the structure in

to bits on the wire.q Examples: Basic Encoding Rules (BER), Packed

Encoding Rules (PER), XML Encoding rules (XER), Distinguished Encoding Rules (DER), ...

q In BER, everything is encoded as Tag-Length-Value.


BER ExampleBER Example

q John Miller, 126 Main Street, Big City, MO 6313030 80 04 0B 4A 6F 68 6E 20 4D 69 6C 6C 65 72Seq. Len Oct Str Len J o h n M i l l e r

02 01 FEInt Len 123

04 0B 4D 61 69 6E 20 53 74 72 65 65 74Oct str 11 M a i n S t r e e t

04 08 42 69 67 20 43 69 74 79Oct Str Len B i g C i t y

04 02 4D 4F 02 02 F6 96 0Oct Str Len M O Int len 63130 Null

7E126

2F

Len

9A


Management Information BaseManagement Information Baseq MIBs follow a fixed naming and structuring convention

Structure of Management Information (SMI)q These conventions were adopted from Common management

Information Protocol (CMIP) designed by ISOq All names are globally uniqueq All nodes of the name tree are assigned numeric values by

standards authoritiesiso.org.dod.internet.mgmt.mib.ip.ipInReceives1.3.6.1.2.1.4.3

q Tables rows are referenced by appending the indexq All names are specified using a subset of Abstract Syntax

Notation (ASN.1)q ASN.1 specifies notation (that humans can read) and encoding

(representation and ranges)


Global Naming HierarchyGlobal Naming Hierarchy

fddimib (73)

fddi (15)

dod (6)

internet (1)

directory (1) mgmt(2) experimental (3)private (4)

mib (1)

system (1) interfaces (2) transmission(10)

ccitt(0) iso (1) joint-iso-ccitt (2)

standard (0)

iso9314 (9314)

fddiMIB (1)

org (3)

fddi (8)

UDP (7)

UDPInDatagrams (1)


MIB Naming Example: UDP ModuleMIB Naming Example: UDP Module

Object ID Name Type Comments

1.3.6.1.2.1.7.1 UDPInDatagrams Counter32 total # datagrams delivered at this node

1.3.6.1.2.1.7.2 UDPNoPorts Counter32 # underliverable datagramsno app at portl

1.3.6.1.2.1.7.3 UDInErrors Counter32 # undeliverable datagramsall other reasons

1.3.6.1.2.1.7.4 UDPOutDatagrams Counter32 # datagrams sent

1.3.6.1.2.1.7.5 udpTable SEQUENCE one entry for each portin use by app, gives port # and IP address


MIB Definition: ExampleMIB Definition: ExampleipAddrTable ::= SEQUENCE of ipAddrEntryipAddrEntry ::= SEQUENCE {ipAdEntAddr ipAddress,ipAdEntIfIndex INTEGER,ipAdEntNetMask ipAddress,ipAdEntBcastAddr ipAddress,ipAdEntReasmMaxSize INTEGER (0..65535)}ipAddrEntry {ipAddrTable 1}ipAdEntNetMask {ipAddrTable 3}


SNMPSNMPq Based on Simple Gateway Management Protocol (SGMP) –

RFC 1028 – Nov 1987q SNMP = Simply Not My Problem [Marshall Rose]

Simple Network Management Protocolq RFC 1058, April 1988q Only Five commands

Command Meaningget-request Fetch a valueget-next-request Fetch the next value (in a tree)get-response Reply to a fetch operationset-request Store a valuetrap An event


SNMP protocolSNMP protocol

Two ways to convey MIB info, commands:

Agent data

Managed device

ManagingEntity

Response

Agent data

Managed device

ManagingEntity

Trap MsgRequest

Request/response mode Trap mode


SNMPv2 PDU TypesSNMPv2 PDU TypesSNMPv2 PDU Type

Sender-Receiver

Description

GetRequest Manager-to-agent

Get value of one or more MIB object instances

GetNextRequest Manager-to-agent

Get value of next MIB object instance in list or table

GetBulkRequest Manager-to-agent

Get values in large block of data, e.g., whole table

InformRequest Manager-to-manager

Inform remote managing entity of MIB values

SetRequest Manager-to-agent

Set value of one or more MIB object

Response Agent-to-Manager

GetRequest, GetNextRequest, GetBulkRequest,SetRequest or InformRequest

SNMPv2 Trap Angent-to- Inform manager of exceptional


SNMP Message FormatsSNMP Message Formats


SNMPv1 ConfigurationSNMPv1 Configurationq Manager sends request to UDP port 161.

Agents send traps to UDP port 162


SNMPv2SNMPv2

q Improved security: authentication and integrity using Data Encryption Standard (DES)

q inform request Multiple manager coordinationLocking mechanisms prevent multiple managers from writing at the same time

q get bulk Better table handlingq Confirmation option for Traps Agents can ensure that trap was received correctly.

q New Error codes: noSuchName, badValue, readOnlyq Reference: RFC 1441, April 1993 and more


SummarySummary

q Management = Initialization, Monitoring, and Controlq SNMP = Only 5 to 7 commandsq Standard MIBs defined for each objectq Uses ASN.1 encodingq SNMPv2 fixed issues with bulk requests and simple security


Review ExercisesReview Exercises

q Try but do not submitq Review Questions: R1 through R12q Problems P1 through P8q Read Pages 771-800


Homework 9Homework 9

q What would be the BER encoding of {firstname “Ed”} {weight 259}? ASN.1 type for octet strings is 4 and for integers it is 2.

network management - cse.wustl.edujain/cse473-11/ftp/i_9mgm.pdf · washington university in st....

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